CHARACTERIZATION OF AEROMONAS SPP ISOLATED FROM HUMANS WITH DIARRHEA,FROM HEALTHY CONTROLS, AND FROM SURFACE-WATER IN BANGLADESH

Aeromonas isolates from patients with diarrhea in Bangladesh (n = 69), from healthy controls (n = 11), and from surface water (n = 40) were analyzed with respect to their hybridization groups (HGs) by the aid o f fatty acid methyl ester (FAME) characterization and DNA fingerprinti ng by AFLP, biochemical phenotypes (PhenePlate [PhP] types), and the p roduction of hemolysin and cytotoxin, The aim of the investigation was to find out whether certain strains carrying virulence factors predom inated among patient isolates, According to FAME and/or AFLP analysis, most human isolates were allocated to DNA HGs 4 (Aeromonas caviae) an d 1 (A. hydrophila). Most environmental strains were allocated to HG8 (A. veronii biogroup sobria) and HG4 (A. caviae), and only one was of HG1, According to PhP typing, the diversity among patient isolates was lower than that among other strains, and two dominating PhP types (ty pes BD-1 and BD-2) were identified in 29 and 30% of the patient isolat es, respectively, PhP type BD-1 was also common among the environmenta l isolates, whereas PhP type BD-2 was only identified in two of the ot her isolates, Twenty-five of 26 isolates belonging to HG1 were of the same PhP type (BD-2), whereas isolates of other common HGs were more d iverse according to their PhP types, Hemolytic and cytotoxin-producing strains occurred more frequently among the environmental isolates tha n among patient isolates, However, the hemolytic and cytotoxic activit ies among human isolates was strongly correlated to the HG1/BD-2 type, which, in addition, showed high cytotoxin titers (median values, 1/51 2 compared to 1/128 for cytotoxin-positive isolates belonging to other types), Thus, the HG1/BD-2 type may represent a pathogenic A. hydroph ila type that is able to produce diarrhea in humans.